NGC
P0123-THROTTLE POSITION SENSOR 1 CIRCUIT HIGH
For a complete wiring diagram Consult Diagrams/Electrical
- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
- Set Condition:
The PCM detects that the Throttle Body input voltage is above the maximum acceptable value.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview
Diagnostic Test
1. DTC IS ACTIVE
NOTE: Diagnose and repair any Throttle Body circuit, system voltage, or sensor supply voltage DTCs before continuing with this test.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
Start the engine and allow it to reach operating temperature.
With the scan tool select View DTCs.
NOTE: If the DTC does not reset it may be necessary to test drive the vehicle.
NOTE: If the P2123-APP Sensor 1 Circuit High DTC is also Active, diagnose the P2123 before continuing with the P0123 diagnostic procedure.
Is the DTC Active at this time?
Yes
- Go to 2
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking For An Intermittent DTC
2. (F855) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Throttle Body connector.
Disconnect the C2 Powertrain Control Module (PCM) connector.
Turn the ignition on.
Measure the voltage of the (F855) 5 Volt Supply circuit in the Throttle Body harness connector.
Is there any voltage present?
Yes
- Repair the (F855) 5 Volt Supply circuit for a short to voltage.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 3
3. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE
Measure the voltage of the (K22) TP Signal 1 circuit in the Throttle Body harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (K22) TP Signal 1 circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 4
4. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (F855) 5 VOLT SUPPLY CIRCUIT
Turn the ignition off.
Measure the resistance between the (K22) TP Signal 1 circuit and the (F855) 5 Volt Supply in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the (K22) TP Signal 1 circuit for a short to the (F855) 5 Volt Supply circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 5
5. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K124) ETC MOTOR (+) CIRCUIT
Measure the resistance between the (K22) TP Signal 1 circuit and the (K124) ETC Motor (+) in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (K22) TP Signal 1 circuit and the (K124) ETC Motor (+) circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 6
6. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K126) ETC MOTOR (-) CIRCUIT
Measure the resistance between the (K22) TP Signal 1 circuit and the (K126) ETC Motor (-) in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (K22) TP Signal 1 circuit and the (K126) ETC Motor (-) circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 7
7. EXCESSIVE RESISTANCE IN THE (K22) TP SIGNAL 1 CIRCUIT
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K22) TP Signal 1 circuit between the Throttle Body harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go to 8
No
- Repair the open in the (K22) TP Signal 1 circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
8. (K922) TP SENSOR GROUND CIRCUIT OPEN
Measure the resistance of the (K922) TP Sensor Ground circuit between the Throttle Body harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go to 9
No
- Repair the open in the (K922) TP Sensor Ground circuit.
- Perform the PCM Verification Test. Powertrain Verification Test
9. THROTTLE BODY
Turn the ignition off.
Connect the C2 Powertrain Control Module (PCM) connector.
Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
Turn the ignition on.
With a scan tool, read the Throttle Body voltage.
NOTE: The sensor voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.
Does the scan tool display the voltage as described above?
Yes
- Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. If OK, replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Go to 10
10. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test. Powertrain Verification Test